Portable electronic devices, such as laptop and notebook computers, dataform readers, barcode readers, portable data terminals, work slates, pen computers, portable electrical testing devices, and touch screen displays typically require the ability to communicate data with an external device. Due to the portability of these devices, they are typically remotely powered by a battery pack, enabling their use without connection to power supply or communication lines. Typically, such devices are equipped with one or more forms of memory and an I/O port, enabling intermittent hook-up to a data communications network for transmitting and receiving information therebetween. Additionally, an AC power supply is frequently provided via a power supply port for intermittently connecting the device to a separate power supply during operation, or for recharging batteries contained therein.
One technique for transferring data and/or verbally communicating with an electronic device such as a computer system involves connecting the device to a public switched telephone network (PSTN) via a telephone modem. For example, a telephone modem, short for modulator/demodulator, is often used on a computer and consists of a communications device that enables the computer to transmit information over a standard telephone line. An RJ-11 jack and connector enable coupling of the computer and modem with a telephone line. The modem converts the digitally formatted information of a computer into an analog signal that is capable of being carried over the telephone line to another computer. The receiving computer has a modem that transfers the analog signal transmitted over the telephone line back into a digital signal usable by the receiving computer. Typically, the modem modulates a computer's digital signal onto a continuous carrier frequency over the telephone line. When receiving, the modem demodulates the information from the carrier, transferring it into digital form for use by the computer. However, it is sometimes inconvenient to utilize a telephone line for coupling together computer systems. In some cases, a hard wire telephone line is not available to a user for use with the computer. For other cases, the computer or electronic device is required to communicate frequently and intermittently with another computer, which would require frequent coupling and decoupling of a telephone line with a jack on the computer to enable portable movement of the computer and subsequent connection after each cycle of use.
According to another way, some portable electronic devices have a dedicated antenna, a cellular radio telephone, and a cellular radio modem configured to enable communication between the device and an external communication device. For example, portable cellular telephones have self-contained antennas for enabling communication with other similar devices via a cellular network. Additionally, laptop and notebook computers have been configured to couple with a cellular telephone via a PCMCIA slot and a connector to enable transmission of data via a cellular modem between the notebook computer and another communications device. However, cellular telephone airtime can be very expensive. Therefore, there is a need for a way to reduce cellular airtime when sending and receiving data in order to reduce cellular airtime charges.
One attempt to reduce cellular airtime costs, or charges, when sending data has been to implement packet data service for first and second generation cellular systems such as the Cellular Digital Packet Data (CDPD) standard. CDPD provides mobile packet data connectivity via an AMPS channel on a shared basis. Since users are charged on a packet-by-packet basis, CDPD typically transfers data at reduced cost. CDPD coexists with a conventional voice-only cellular system such as AMPS, but it capitalizes on the unused air time which occurs between successive radio channel assignments by the Mobile Switching Center (MSC). However, many applications still require that a considerable amount of data and/or voice communication be implemented. For example, warehouse personnel performing inventory analysis and/or processing orders in a warehouse with portable computing devices having wireless communications capabilities still must transfer a large amount of data, incurring substantial cellular connection charges. Therefore, there is a need to reduce commercial cellular connection charges when performing data/voice transmissions within a defined geographic location such as a warehouse or factory.
The present invention relates to an improved portable electronic device having wireless communications features that minimize use of commercial cellular networks when transmitting data/voice between the device and another device.